The present invention relates to a liquid crystal display module and a liquid crystal display monitor mounting the liquid crystal display module.
The liquid crystal display devices have been widely used as a display device capable of displaying high-definition color images for a notebook personal computer and a display monitor. The liquid crystal display device comprises a liquid crystal display panel having a liquid crystal layer sandwiched between a pair of transparent substrates, an illuminating device for visualizing latent images electronically formed in the liquid crystal display panel, and an optically compensating sheet disposed between the liquid crystal display panel and the illuminating device. These components can be assembled as an integral unit which is capable of being mounted into a notebook personal computer or a liquid crystal display monitor, and which is commonly called a liquid crystal display module.
Among the well-known liquid crystal display devices, one type is a simple-matrix type liquid crystal display device incorporating a simple-matrix type liquid crystal display panel having a liquid crystal layer sandwiched between a pair of substrates each formed with parallel strip electrodes on their inner surfaces arranged such that the parallel strip electrodes on one of the pair of substrates intersect those on the other of the pair of substrates, and another type is an active-matrix type liquid crystal display device incorporating a liquid crystal display panel provided with switching elements on one of a pair of substrates sandwiching a liquid crystal layer such that each of the switching elements selects a corresponding one of pixels of the liquid crystal display panel.
The active-matrix type liquid crystal display panel is divided into a so-called vertical electric field type (commonly called the TN type) which is represented by the TN (Twisted Nematic) type and uses a liquid crystal display panel having plural strip electrodes formed on each of a pair of upper and lower substrates for selecting pixels, and a so-called horizontal electric field type (commonly called IPS (In-Plane Switching) type) which uses a liquid crystal display panel having plural electrodes formed only on one of a pair of upper and lower substrates for selecting pixels.
In the TN type liquid crystal display panel, the liquid crystal molecules are aligned to twist by 90 degrees, for example, between a pair of upper and lower substrates, a pair of polarizers are disposed on the outer surfaces of the upper and lower substrates of the liquid crystal display panel, respectively, with their absorption axes oriented in the cross-Nicole arrangement, and the absorption axis of the entrance-side polarizer is aligned in parallel with or perpendicularly to a rubbing direction of the entrance-side substrate.
In the TN-type active-matrix type liquid crystal display panel, when a voltage is not applied across the liquid crystal layer, the linearly polarized light entering the liquid crystal layer through the entrance-side polarizer propagates along the twist of the liquid crystal molecules of the liquid crystal layer, if the transmission axis of the exit-side polarizer is coincident with the azimuthal angle of the plane of polarization of the linearly polarized light leaving the liquid crystal layer, all the linearly polarized light exits from the liquid crystal display panel 1 to produce a white display (the so-called normally open mode), but, on the other hand, when a voltage is across the liquid crystal layer, a director which is a unit vector representing a direction of the average alignment of the axes of the liquid crystal molecules of the liquid crystal layer is perpendicular to the major surface of the substrate, therefore the azimuthal angle of the plane of polarization of the linearly polarized light entering the liquid crystal layer is not changed, and consequently, the azimuthal angle of the plane of polarization of the linearly polarized light leaving the liquid crystal layer becomes coincident with that of the absorption axis of the exit-side polarizer, and produces a black display (For further detail, see xe2x80x9cBasics and Application of Liquid Crystal,xe2x80x9d Industrial Research Association, Tokyo, 1991.).
On the other hand, in the IPS type liquid crystal display panel which has plural electrodes and wiring therefor for selecting pixels formed only on one of a pair of substrates, switches the liquid crystal molecules in planes parallel with the major surface of the substrates by applying a voltage between adjacent electrodes (a pixel electrode and a counter electrode) on the substrate, the polarization axes of the polarizers are arranged so as to produce a black display when no voltage is applied between the adjacent electrodes (the so-called normally closed mode).
In the IPS type liquid crystal display panel, the liquid crystal molecules in an initial state are in a homogeneous orientation in which the axes of the liquid crystal molecules are parallel with the major surfaces of the substrates, and the director of the liquid crystal molecules are parallel with or inclined at a small angle with a direction of the electrode wiring in planes parallel with the major surfaces of the substrates when no voltage is applied between the adjacent electrodes, and if a voltage is applied between the adjacent electrodes, the director of the liquid crystal molecules rotates toward a direction perpendicular to the direction of the electrode wiring according to the applied voltage. When the director is inclined at 45 degrees with respect to a direction of the director where no voltage is applied between the adjacent electrodes, the liquid crystal layer having a voltage thereacross serves to rotate the the azimuthal angle of plane of polarization through 90 degrees like a half-wave plate such that the azimuthal angle of plane of polarization of the light becomes coincident with the transmission axis of the exit-side polarizer, resulting in production of a white display.
The IPS type liquid crystal display panel has advantages that hue and contrast of a display vary little with viewing angles and consequently, their viewing angles are increased (See Japanese Patent Application National Publication No. Hei 5-505, 247 published on Aug. 5, 1993 which corresponds to WO91/10936 of PCT).
The most commonly used system for producing a full color display in the liquid crystal display devices using the above-explained types of liquid crystal display panels is one using color filters. In this system, one pixel corresponding to one dot capable of producing a color display is subdivided into three subpixels provided with three color filters corresponding to three primary colors, red (R), green (G) and blue (B), for example, respectively.
Recently, the liquid crystal display devices have been increased in screen size and in display resolution, and hence the liquid crystal display modules incorporated into the liquid crystal display device have been increased in weight. As for an external shape of the liquid crystal display modules, there has been a strong demand for reduction of a border area around a useful display area of a notebook personal computer or a liquid crystal display monitor incorporating such liquid crystal display modules. This is attributable to a demand that the outside dimensions of the notebook personal computer or the liquid crystal display monitor be made as small as possible. Hereinafter, the notebook personal computer and the liquid crystal display monitor may be referred to as the liquid crystal display monitor and the like.
The small outside dimensions can mean a superior saving in space, and as for design, the screen area of the liquid crystal display monitor appears larger if its border area around its useful display area is made smaller.
One of problems to be solved in design for realization of reduction of a border area around a useful display area is how to mount a liquid crystal display module on a display section of a personal computer, a liquid crystal display monitor or the like.
FIGS. 24A-24C are rough illustrations of conventional means for mounting a liquid crystal display module on a liquid crystal display monitor and the like, FIG. 24A is a front view of the liquid crystal display module, FIG. 24B is a side view of the liquid crystal display module of FIG. 24A, and FIG. 24C is an enlarged perspective view of a corner portion of the liquid crystal display module and a portion of the liquid crystal monitor corresponding to the corner portion of the liquid crystal display module of FIG. 24A.
In a liquid crystal display module MDL, a liquid crystal display panel PNL and an illuminating device (a backlight) are fixed together by an upper frame SHD shaped from a metal material to be provided with a shielding function and to serve as an upper case and a lower frame (here a molded case MCA) which serves as a lower case. This backlight is of the so-called edge light type comprising a light guide made of a transparent plate and a line light source disposed at its edge, but only a light guide GLB is shown in FIG. 24C.
Incidentally, the lower frame is not limited to the molded case MCA shaped from a resin material as shown in FIGS. 24A-24C, but a lower frame is also known which is comprised of an intermediate molded frame configured to hold components such as the illuminating device in place and a metal plate disposed behind the intermediate molded frame. In this specification, a lowermost component of the liquid crystal display module is referred to as the lower frame, and the above-mentioned metal plate may be referred to as a rear frame.
A front surface of the upper frame SHD in the form of a rectangular peripheral frame is formed with a recessed portion ALC set back from the front surface in a direction perpendicular to it, and a mounting hole (a hole for receiving a screw) HLD is made in a bottom of the recessed portion ALC. A mounting screw SCR passed through the mounting hole HLD engages with a tapped hole NAT made in a screw-receiving boss BOS provided to a housing CAS of the monitor or the like to fix the module and the housing together.
Incidentally, the molded case MCA shaped from a resin material is used as the lower frame in FIGS. 24B and 24C, but, even if the lower frame is made of metal like the upper frame, the module and the housing of the monitor can be fixed together by the similar mounting structure.
However, with such a mounting structure, there is a limit to reduction of the width W of a border area of the upper frame SHD, a bead or the like needs to be formed around the mounting hole HLD to add to the strength of the portion around it, and consequently, it is difficult to realize the reduction of a border area around a useful display area of the liquid crystal display module.
In another exemplary conventional mounting structure, screw-receiving holes are made in sidewalls of a liquid crystal display module, and the module is secured to a housing of a liquid crystal display monitor or the like by screws extending from the housing into the module and engaging with the screw-receiving holes. In this mounting structure, mounting bosses (members for covering screws, or naves) need to be provided to the housing of the liquid crystal display monitor or the like, therefore the outside dimensions of the housing are increased, and consequently, it is difficult to satisfy the demand that the outside dimensions of the housing of the liquid crystal display monitor and the like be made as small as possible.
As explained above, in the conventional mounting structure for securing the liquid crystal display module to the housing of the liquid crystal display monitor and the like, the width of a border area of the upper frame needs to be wide enough to secure the mechanical strength of tapped holes and portions around the tapped holes, and consequently, it is difficult to realize the required reduction of the width of a border area of the upper frame and the required reduction of the outside dimensions of housings of the monitors and the like.
It is an object of the present invention to eliminate the above-explained problems with the prior art and thereby to provide a liquid crystal display module provided with a novel mounting structure for mounting the liquid crystal display module on a liquid crystal display monitor and the like which is capable of realizing the reduction of the width of a border area of the upper frame of the liquid crystal display module and the reduction of the outside dimensions of housings of a liquid crystal display monitor and the like, and to provide a liquid crystal display monitor mounting the liquid crystal display module.
To accomplish the above-mentioned object, in an embodiment of the liquid crystal display module in accordance with the present invention, the liquid crystal display module is provided with a recessed portion in its outermost sidewall and a screw-receiving hole made in the recessed portion for side mounting. Placement of the screw-receiving hole in the sidewall of the liquid crystal display module makes possible the reduction of a border area around a useful display area of the liquid crystal display module. In the structure of mounting the liquid crystal display module on a display section of a liquid crystal display monitor and the like, placement of a mounting boss in a portion of a housing of the liquid crystal display monitor corresponding to the recessed portion suppresses enlargement of the outside dimensions of the liquid crystal display monitor and the like.
The boss is placed into the recessed portion of the liquid crystal display module, a screw is put into the liquid crystal display module through the mounting boss from the side of the liquid crystal display monitor, and the screw fixes the liquid crystal display module to the liquid crystal display monitor. This mounting structure eliminates the need for increasing the outside dimensions of the liquid crystal display monitor. In this structure, provision of a tapped hole in a molded frame of the liquid crystal display module makes possible the side mounting as in the case of the conventional mounting structure.
If the mounting boss is fabricated integrally with the housing of the liquid crystal display monitor in advance, an additional component is not necessary and the assembly is facilitated. Placement of the tapped holes in the molded frame having the greatest volume in the liquid crystal display module facilitates absorption of external vibrations and shocks. The tapped hole can be made directly in the molded frame, but preferably a metal member formed with the tapped hole, that is, a so-called insert, is embedded in the molded frame beforehand, thereby the mounting strength is increased, and consequently, this mounting structure is capable of maintaining the firm mounting external vibrations and shocks.
The present invention is not limited to the side mounting type, but is also applicable to the rear mounting type in which a liquid crystal display module is fixed to a housing of the liquid crystal display monitor or the like at the rear of the liquid crystal display module. In this case, tapped holes are made in the rear surface of a molded case of the liquid crystal display module. The tapped holes can be made directly in the molded case, or may be made in an insert embedded in the molded case. The reduction of a border area around a useful display area is facilitated because there is no necessity for making tapped holes or the like in the sidewall of the liquid crystal display module, and consequently, the outside dimensions of the liquid crystal display monitor or the like can be reduced. In a case where a downlight type illuminating device (a downlight type backlight) is used in the liquid crystal display module, if the tapped holes are made in portions of the molded case corresponding to peaks of a corrugated reflective plate of the backlight, the liquid crystal display module can be fixed to the housing of the liquid crystal display monitor or the like without increasing the thickness of the liquid crystal display module.
The following explains the representative configurations of the liquid crystal display module and the liquid crystal display monitor (including application to TV receiver sets and the like in addition to computer terminals) in accordance with the present invention.
In accordance with an embodiment of the present invention, there is provided a liquid crystal display module comprising: a liquid crystal display panel having a liquid crystal layer sandwiched between a pair of substrates; an illuminating device disposed behind the liquid crystal display panel; an upper frame; and a lower frame, the upper frame and the lower frame fixing therebetween the liquid crystal display panel and the illuminating device as an integral unit in cooperation with each other, and the upper frame being provided with at least one recessed portion in a sidewall thereof, the at least one recessed portion being set back in a direction parallel with major surfaces of the pair of substrates from the sidewall, and a bottom of the at least one recessed portion being provided with a tapped hole adapted for engagement with a screw for mounting the liquid crystal display module to external equipment.
In accordance with another embodiment of the present invention, there is provided a liquid crystal display module comprising: a liquid crystal display panel having a liquid crystal layer sandwiched between a pair of substrates; an illuminating device disposed behind the liquid crystal display panel; an upper frame; and a lower frame, the upper frame and the lower frame fixing therebetween the liquid crystal display panel and the illuminating device as an integral unit in cooperation with each other, and the upper frame being provided with at least one recessed portion in a sidewall thereof, the at least one recessed portion being set back in a direction parallel with major surfaces of the pair of substrates from the sidewall, a bottom of the at least one recessed portion being provided with a hole adapted for passing therethrough a screw for mounting the liquid crystal display module to external equipment, and a portion of the lower frame facing the hole being provided with a tapped hole adapted for engagement with the screw.
In accordance with another embodiment of the present invention, there is provided a liquid crystal display module comprising: a liquid crystal display panel having a liquid crystal layer sandwiched between a pair of substrates; an illuminating device disposed behind the liquid crystal display panel; an upper frame; and a lower frame, the upper frame and the lower frame fixing therebetween the liquid crystal display panel and the illuminating device as an integral unit in cooperation with each other, and the lower frame being provided with at least one tapped hole in a rear surface thereof adapted for engagement with a screw for mounting the liquid crystal display module to external equipment.
In accordance with another embodiment of the present invention, there is provided a liquid crystal display monitor comprising: a liquid crystal display module including a liquid crystal display panel having a liquid crystal layer sandwiched between a pair of substrates, a first frame and a second frame, the first and second frames fixing the liquid crystal display panel therebetween in cooperation with each other, the first frame being provided with a first sidewall extending along a periphery of the pair of substrates and in a direction of a thickness of the liquid crystal display panel outside of the second frame, the first sidewall being provided with at least one recessed portion set back inwardly from the first sidewall; and a housing having a mounting structure facing the at least one recessed portion, the mounting structure being provided with a screw directed toward the at least one recessed portion such that the liquid crystal display panel is fixed to the housing.
In accordance with another embodiment of the present invention, there is provided a liquid crystal display monitor comprising: a liquid crystal display module including a liquid crystal display panel having a liquid crystal layer sandwiched between a pair of substrates, a first frame and a second frame, the first and second frames fixing the liquid crystal display panel therebetween in cooperation with each other, the first frame being provided with a sidewall extending along a periphery of the pair of substrates and in a direction of a thickness of the liquid crystal display panel outside of the second frame; and a housing having a mounting structure facing an outer surface of the first frame and mounting the liquid crystal display panel to the housing, the mounting structure being provided with at least one screw directed toward the sidewall of the first frame for affixing the liquid crystal display panel to the mounting structure, wherein each of the sidewall of the first frame and the mounting structure is provided with a hole for passing each of the at least one screw therethrough, a sidewall of the second frame is provided with a tapped hole for engagement with the at least one screw, and a thickness of the sidewall of the second frame at least in the vicinity of the tapped hole is greater than that of the sidewall of the first frame in the vicinity of the hole provided therein.
In accordance with another embodiment of the present invention, there is provided a liquid crystal display monitor comprising: a liquid crystal display module including a first frame, a liquid crystal display panel having a liquid crystal layer sandwiched between a pair of substrates, an illuminating device disposed behind the liquid crystal display panel, and a second frame arranged in the order named, the first and second frames fixing the liquid crystal display panel and the illuminating device therebetween in cooperation with each other; a housing having a mounting structure facing a rear surface of the second frame and mounting the liquid crystal display panel to the housing, the mounting structure being provided with at least one hole for passing at least one screw therethrough for affixing the liquid crystal display panel to the mounting structure, the rear surface of the second frame being provided with at least one tapped hole for engagement with each of the at least one screw, and a thickness of the rear surface of the second frame in the vicinity of the at least one tapped hole being greater than that of the remainder of the rear surface.
The present invention is not limited to the above configurations, but various changes and modifications may be made without departing from the nature and spirit of the invention. Other objects and configurations of the present invention will be apparent upon consideration of the following detailed description and the drawings.